For anyone who doesn't know, I'm a massive physics nerd. Physics is great, in some cases it knows exactly what's going on and can predict is really accurately. But in other cases it can model something, but all that we really know for certain is how little we really know about the topic, and one of the most famous cases of this is the atom.
Humans seem to love making things, our creativity is one of the things that defines us, setting us apart from the bacteria and fungi that we share this planet with. But there have been times where in order to make new things, we have had to have a greater understanding of what we're making them out of.
We have always been looking closer and closer, building microscopes to detect light and even electrons in an attempt to figure out what everything is made of, probing deeper and deeper, trying to find the indivisible individual sections of matter that make up everything. The atom may not be the simple individual piece that we're looking for but it is a truly beautiful system, made up of a complex structure of matter and balanced charges.
In this post I'll explain the classical model of the atom, where we assume everything is all nice and tidy and made of particles and not a quantum mess of clouds of charge and such.
So lets begin with the biggest part, the atom itself, the largest atom known to us is that of Cesium (CS) which has a radius of around 270 pm. Lets put that in perspective, 1 pm is 1x10^-12 m or in an easier to understand format, 0.000000000001 m that means that one of these atoms is 0.000000000540 m across. Pretty small right? Guess again because that's not as small as an atom gets, the smallest atom possible is that of helium, with a minuscule radius of 31 pm, nearly 9 times smaller! OK fine that's really not that much smaller in the sense of things, until you realise that's the difference between the Arc De Triomphe and the Empire State Building!
So that's how big they are, or more accurately how small they are, I mean there's more atoms in a grain of sand than there are grains of sand on Earth!
Anyway moving on, next layer, AKA the electrons! Who doesn't love electrons? They power our gadgets, they're thought to be fundamental particles, they do all kinds of cool stuff with light and charged particles and they supposedly orbit neatly in shells of 2, 8 and 8 right? Wrong.
Electrons are great little things, but they are by no means straightforward. The fact that they repel means that when they are orbiting an atom they take up positions that will allow them to be as far away as possible from the other, so one is fine by itself, two will be on opposite sides of the nucleus, three will be in a triangle and 4 will be a tetrahedron and so on and so forth.The chart on the right is a bit of a preview to next time but also shows just how incredibly complex these seemingly simple little lumps of negativity can be.
And it only gets weirder.
Now on to the next part of the atom, the nucleus, a region which is so dense that if we could fill 1 cubic meter with the nuclei of atoms (they're all roughly equally dense) it would weight roughly 2.7x10^17 kg, which is equivalent to 77500000000 Saturn V rockets. ItIhelps to visualise to say that if the moon was compressed to this density from its current average density of 3347 kg/m3 then it would have a new surface area of 22600 meters squares, roughly the size of 1 quarter of Ireland. So yeah its pretty incredibly dense, and as the electron's mass pales in comparison we tend to just say that the mass of the nucleus is the mass of the atom.
But now we must leave out electrifying friends as we have to go deeper!
Anyone who has done GCSE physics will know that the nucleus contains protons and neutrons, the positively charged particles that keep the electrons around and the neutral particles really don't do much more than add more mass and stability to the nucleus.
But lets look a little closer shall we? Firstly the proton. This particle is the optimist of the atomic trio, constantly positive with a charge of +1. Its is also spinning constantly as are all of the particles, and as it is spinning, the motor effect dictates that a small magnetic field is generated. And that is pretty much it, it is also interesting to note that as a hydrogen nucleus is simply 1 proton by itself, we find a lot of protons simply floating around as either Hydrogen atoms or alone as Hydrogen + ions.
Secondly the neutron, this is actually sightly more simple than the proton, the neutron consists of quarks which have charges that actually balance out to 0 making it a completely neutral particle (hence the name). The neutron just kind of sits there, spinning around and adding a bit of mass, sometimes it may influence the spin of an electron but that is really one of the only significant effects that the particle has.
However when we look at what happens to the system as a whole under different circumstances, it gets a lot more interesting, for example, while the strong force can easily bind together a nucleus with the same amount of protons and neutrons, once there is an imbalance, things start to get a little bit tricky. Through quantum mechanical processes, the nucleus can literally beak apart over and over again, emitting alpha particles (helium nuclei) until it is eventually stable enough to bind the particles together better. We call this radioactive decay (although there are two other types that occur in different ways to this one).
Does anyone think this is as small as things get? If you did then you're completely wrong and need to remember that physics does not comply or cooperate with us willingly. Ever. Scientists in the late 60s decided they wanted to see what was inside these particles, so naturally they got a big particle acceleration machine and smashed things into each other until they found their answer. (yay physics!)
What they found was extremely interesting, when you fire an electron at a proton with enough speed it will actually go through the proton, however it is deflected by what appear to be 3 point charges within the proton. The same applies to the neutron. The physicists who predicted this before the experiments were carried out had creatively chosen the name "Quarks" pronounced "kworks" as opposed to a traditional physicsy name like subnucleonic particles, which is frankly refreshing considering how wildly creatively science as a whole has named most things (yes I'm talking about you chemistry with all of your naming systems!).Quarks make up protons and neutrons, there are 6 flavours of quark called up, down, strange charm, top and bottom, they all possess a charge of either 2/3 or 1/3 (positive or negative) and they also posess colour charge because normal charge is not enough for them, and as a result of this, cannot exist alone and I swear that I did not make up any of that, those are actually the correct names and terms.
Personally I'm looking forward to the names that they will come up with for more advancements in this field just as much as the science itself!
At the moment we have no idea what is inside a quark, for all we know it might be fundamental, and until we can prove it experimentally we have no clues other than theoretical maths created to support theories. However physicists at the Large hadron Collider (LHC) are doing exactly that, being unsure if the LHC can actually provide enough energy to break a quark into bits, they are instead aiming to make one excited (energetic) in the hopes that they can tell from the energy emissions whether or not it has a substructure.
And there we have it, from atomic radii to quarks, that is the nuclear model of the atom, which is surprisingly not able to explain everything, considering the amount of detail it consists of. But anyway whats a story for next time.
If any of you saw the date yes I did spend lots of Halloween typing this but I already went to Halloween party this week and can't cope with continuing my walking dead marathon at night when its dark so don't judge me!
Anyhow its getting late and I am tired so I'll leave it there for today, has it occurred to you yet that particle physicists are a bunch of atoms trying to understand themselves? Yep our universe it that awesome and weird and clever and generally crazy.
On that note I shall leave you all once more, Happy Halloween to you all and I'll post again soon! :)
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